This five year project proposes to investigate orofacial pain from a multidisciplinary perspective. Eight projects representing investigators and co-investigators in a variety of professional fields and of varying University affiliations will investigate the anatomy, physiology, psychology and modulation of the orofacial pain experience. Each research project will collaborate directly with one or more of the other projects. The goals of the program project as a whole are the gain knowledge about the anatomy, neurophysiology, psychology and mechanisms of orofacial pain and pain syndromes, and to contribute to the general scientific knowledge of pain and pain management. Research using animal subjects will investigate: 1) the ultrastructure of dental receptor mechanisms, 2) near-field and far-field cerebral evoked potentials to painful dental stimulation, 3) and modulation of painful stimulation with drugs. In addition, a magnetic field tooth pulp stimulator will be constructed and tested in all three of these laboratories. These investigators will actively collaborate with one another, sharing resources, animal subjects and facilities. Human subject investigations will study: 1) cerebral evoked response to painful tooth pulp stimulation in man, 2) modulation of response to painful dental stimulation by counter-irritation and manipulation of endogenous opiate-like substances, 3) pain perception and modulation in the dental clinic, and 4) patterns of pain symptomatolgy and personality factors in facial pain patients. There will be collaboration among animal and human subject investigators in work on cerebral evoked response to orofacial pain. Pain in the face, head, and neck is a major dental/medical problem as well as a social problem in the United States. The information gained by this program project is expected to contribute significantly to the management of both chronic and acute pain states in dentistry and medicine.